linux-kernel - Re: [PATCH v11 08/14] HP BIOSCFG driver

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Message-ID: <CAOOmCE8iBfeuodTO7C=0EUOkqv16008h7vsZO2hhBZPuLoLECw@mail.gmail.com>
Date:   Fri, 28 Apr 2023 11:03:56 -0500
From:   Jorge Lopez <jorgealtxwork@...il.com>
To:     Thomas Weißschuh <thomas@...ch.de>
Cc:     hdegoede@...hat.com, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 08/14] HP BIOSCFG driver - bioscfg-h

On Fri, Apr 28, 2023 at 10:36 AM Thomas Weißschuh <thomas@...ch.de> wrote:
>
> On 2023-04-28 10:24:40-0500, Jorge Lopez wrote:
> > On Sun, Apr 23, 2023 at 7:01 AM Thomas Weißschuh <thomas@...ch.de> wrote:
> > >
> > > On 2023-04-20 11:54:48-0500, Jorge Lopez wrote:
> > > > ---
> > > >  drivers/platform/x86/hp/hp-bioscfg/bioscfg.h | 613 +++++++++++++++++++
> > > >  1 file changed, 613 insertions(+)
> > > >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/bioscfg.h
>
> <snip>
>
> > > > +/* global structure used by multiple WMI interfaces */
> > > > +extern struct bioscfg_priv bioscfg_drv;
> > > > +
> > > > +enum hp_wmi_data_type {
> > > > +     HPWMI_STRING_TYPE               = 0x00,
> > > > +     HPWMI_INTEGER_TYPE              = 0x01,
> > > > +     HPWMI_ENUMERATION_TYPE          = 0x02,
> > > > +     HPWMI_ORDERED_LIST_TYPE         = 0x03,
> > > > +     HPWMI_PASSWORD_TYPE             = 0x04,
> > > > +     HPWMI_SECURE_PLATFORM_TYPE      = 0x05,
> > > > +     HPWMI_SURE_START_TYPE           = 0x06
> > > > +};
> > >
> > > Unused.
> >
> > Both hp_wmi_data_type and hp_wmi_data_elements are used
> > for instance  HP_WMI_STRING_TYPE
> >
> > bioscfg.c:338: case HPWMI_STRING_TYPE:
> > bioscfg.c:626: case HPWMI_STRING_TYPE:
> > bioscfg.c:722: case HPWMI_STRING_TYPE:
> > bioscfg.c:798: case HPWMI_STRING_TYPE:
> > bioscfg.c:906: ret = hp_init_bios_attributes(HPWMI_STRING_TYPE,
> > HP_WMI_BIOS_STRING_GUID);
> > bioscfg.h:247: HPWMI_STRING_TYPE
>
> Indeed. I think I just searched for "hp_wmi_data_type".
>
> The proper enum hp_wmi_data_type type should be used instead of
> "int attr_type".
>

Done!

> <snip>
>
> > > > +
> > > > +enum hp_wmi_elements_count {
> > > > +     STRING_ELEM_CNT         = 12,
> > > > +     INTEGER_ELEM_CNT        = 13,
> > > > +     ENUM_ELEM_CNT           = 13,
> > > > +     ORDERED_ELEM_CNT        = 12,
> > > > +     PASSWORD_ELEM_CNT       = 15
> > > > +};
> > >
> > > To make it clearer where these values come from you could put them into
> > > the enum hp_wmi_data_elements.
> > >
> > > ...
> > >         ORD_LIST_ELEMENTS = 11,
> > >         ORD_LIST_ELEM_CNT = 12,
> > > ...
> >
> > Done!  changes provided across all files affected.
> >
> > >
> > > But replacing the loop logic would remove the need for these enums
> > > completely.
> > >
> >
> > _CNT values are necessary when elements are read from a buffer (
> > populate_string_elements_from_buffer).
> > _CNT values are not needed when elements are read from a package
> > (populate_string_package_data)
>
> Hm, I don't see why populate_string_elements_from_buffer() would need
> the _CNT define.
>
> (In another review mail I wrote down how I would expect it to look
> without the loop)
>
> <snip>
>
> > > > +
> > > > +#define ATTRIBUTE_PROPERTY_STORE(curr_val, type)                     \
> > > > +     static ssize_t curr_val##_store(struct kobject *kobj,           \
> > > > +                                     struct kobj_attribute *attr,    \
> > > > +                                     const char *buf, size_t count)  \
> > > > +     {                                                               \
> > > > +             char *p = NULL;                                         \
> > > > +             char *attr_value = NULL;                                \
> > > > +             int i;                                                  \
> > > > +             int ret = -EIO;                                         \
> > > > +                                                                     \
> > > > +             attr_value = kstrdup(buf, GFP_KERNEL);                  \
> > > > +             if (!attr_value)                                        \
> > > > +                     return -ENOMEM;                                 \
> > > > +                                                                     \
> > > > +             p = memchr(attr_value, '\n', count);                    \
> > > > +             if (p != NULL)                                          \
> > > > +                     *p = '\0';                                      \
> > >
> > > This can also truncate the string if there is data after the newline.
> >
> > This is a expected behavior as described by Hans in a later email
>
> I'm fine with stripping a trailing newline.
>
> But this truncates the string at the first newline.
>
> "foo\nbar" -> "foo"
> "\nfoo" -> ""
>
All inputs expected by this driver and respectively by BIOS are a
single line.  For this reason, '\n' will cause the string to be
truncated.
I propose reporting a warning message indicating that the data entered
has a '\n' character and will be truncated in addition to failing the
operation with -EINVAL


> <snip>